Biology of rice weevil, Sitophilus oryzae Linn. (Coleoptera: Curculionidae) in stored wheat Triticum vulgare and its control

摘要

The biology, host preference, and control of S. oryzae were studied under laboratory conditions. The total number of eggs laid was 225 on wheat, 160 on jowar [sorghum], 115 on maize, and 54 on rice, indicating that fecundity is high on preferred hosts. The developmental period of S. oryzae was shortest but the survival period longest (41 days) on wheat (35 days). The incubation period varied from 5 to 7 days. Egg viability was low in winter but high in summer. High temperature shortened the incubation and preoviposition periods and, as high humidity, increased hatching percentage. The largest male and female individuals were observed on maize, as grain size was directly correlated with body size. The efficacy of Azadirachta indica leaf extracts (70, 90, and 100%) to control weevil population on hosts increased with the increase in extract concentration. The highest control rate of 80-90% was obtained with 100% leaf extract.